1. Field of the Invention
The invention pertains to the field of personal identification systems.
2. Description of the Related Art
Many personal identification techniques have been invented to avoid fraud. The most promising identification technique is based on smart cards, wherein a complete microprocessor is integrated in a module that fits in the thickness of a standard plastic credit card. The operations performed by the microprocessor and the exchange of information with a host computer via a reader are entirely secured using robust encryption techniques. There is also a need to store significant amounts of personal information such as for, example, medical history. Again, smart cards are ideally suited for this type of data storage.
Smart cards are well established in Europe and are starting to appear in other parts of the world. However, despite their obvious benefits, smart cards have not been adopted for identical applications in all countries. The principal obstacle to wide adoption of smart cards is the complexity, fragility and cost of the hardware devices. The smart module as well as the reader can be too easily damaged if minimal caution is not taken.
A very promising technique that is based on printing very fine symbols directly on the surface of the card together with text identification data, photograph, finger print, signature, and logos is a robust and inexpensive solution to the personal identification problem. For example, Symbol Technology has created the PDF code and Xerox has created the DataGlyph code. The PDF code is a two-dimensional code that is used for the identification of factory items, and is read using handheld laser beam scanning technique. The DataGlyph code, a two-dimensional code, patented by Xerox, (U.S. Pat. No. 5,245,165), is used to provide additional information on office forms that are scanned using a conventional general-purpose document reader.
The DataGlyph code is composed of symbols almost invisible to the naked eye and the general patterns typically appear as uniform gray shading that can be inserted for filling gaps between large letters, logos or photographs. Printed at 300 dpi, these patterns store about 400 bytes per square inch. The DataGlyph code is, therefore, ideally suited to be printed on personal identification plastic cards using 300 dpi thermal transfer printers, or higher resolution printing techniques, for storing encrypted data such as medical information, fingerprints, photographs, signatures, and any other biometrics digitized data.
Once the printed information is digitized using a document-imaging scanner, a pattern recognition algorithm identifies the symbols and translates them back into their binary form. Robust redundancy algorithms such as the Cross-Interleaved Reed-Solomon code used in spacecraft transmissions and CD-ROM readers allow a high percentage of symbol errors to occur before the encoded original message is unrecoverable. Typically, error rates up to 30% can still result in successful decoding. Each user determines the amount of error correction to be used, depending on the expected damage or abuse that may be sustained by the card in that application.
This tolerance to a high rate of errors make this personal identification technique extremely robust even in harsh environments. The plastic cards are not affected by dust, humidity, corrosion, temperature or sweat. Tampering is rapidly identified. Typically, printed cards cost 1/10th the cost of smart cards.
Other symbol-based technologies that make use of laser beam techniques to print and read the information are less robust and considerably more expensive.
The devices in the prior art that can digitize information printed on personal identification cards are general-purpose document scanners that are not suited for heavy-duty usage and fast reading of ID cards.